switch (data) {
                case "一年": myDate.setFullYear(myDate.getFullYear() + 1);
                    etime = myDate.toLocaleDateString();
                    break;
                case "半年": myDate.setMonth(myDate.getMonth() + 6);
                    etime = myDate.toLocaleDateString();
                    break;
                case "季度": myDate.setMonth(myDate.getMonth() + 3);
                    etime = myDate.toLocaleDateString();
                    break;
            }
判断选择的是那个， 然后重新给结束时间赋值